In the making of glass, glass forming materials are provided into a glassmelter and melted into molten glass which is then poured into molds to produce products such as, for example, glass bottles. It is important that the molten glass be well mixed and also that it flow smoothly so that high quality glass results from the glass making process. In order to assure the production of high quality glass, viscosity-reducing flux material is employed as part of the glass forming materials charged into the glass melter. Alkali compounds such as sodium oxide, potassium oxide and lithium oxide are the principal fluxes used in commercial glass production.
Generally, the alkali flux material is the most expensive of the principal glass forming materials. Moreover, a significant amount of alkali flux material must be used in order to adequately achieve the requisite viscosity reduction and other beneficial properties of glass. For example, in a typical soda-lime-silicate glass, about 13 to 16 weight percent of the glass is alkali oxides, e.g. sodium oxide. Thus, it is desirable to reduce the amount of alkali oxide flux material used in glass manufacturing.
It is known that water acts as an effective fluxing agent in glassmaking operations by forming hydroxyl groups in the glass molecular structure. In an effort to supply increased quantities of hydroxyl groups to molten glass in a glassmelting operation, a number of methods have been tried. For example, steam or moist air has been bubbled through molten glass in an electrically heated glassmelting furnace, heating with hydrogen based combustion has been carried out, either above the glass surface or by submerged combustion, and alkali hydroxyl compounds such as sodium hydroxide, potassium hydroxide and lithium hydroxide have been added to the glass batch during melting. None of these methods is used to reduce alkali flux in large commercial furnaces due to the higher costs of these methods.
Accordingly, it is an object of this invention to provide an economical method for producing glass having a reduced alkali content.